Games

History:
http://www.ciconline.org/eLECTIONS - an election game.
http://pbskids.org/democracy/presforaday/index.html - become president for a day.

Mathematics:
http://www.coolmath-games.com/lemonade/ - run your own business, a lemonade stand!

http://www.rocketsnail.com/mancala/game.htm - a mancala game, for one or two.

http://dsc.discovery.com/tv/future-weapons/games/cannon/cannon.html - an artillary game.